Kutcher, 34, has signed up to be the 500th "astronaut customer," Branson wrote. Explained the mogul, "I gave Ashton a quick call to congratulate and welcome him. He is as thrilled as we are at the prospect of being among the first to cross the final frontier (and back!) with us and to experience the magic of space for himself."

"Ashton is joining a fast expanding group of true pioneers who are on their way to a life changing experience and a place in the history books," Branson wrote of the tech-savvy "Two and a Half Men" actor. "It's great to have him on board."